The news comes as Virgin Media issued a sales memorandum yesterday for Virgin Media Television and its ad sales house IDS, though it excluded its 50% stake in UKTV from the auction.
Webb, who is promoted from managing director of VMTV, has also been given responsibility for IDS.
However, while Wall's role included the chairmanship of UKTV, the new position taken by Webb appears not to bear any responsibility for the 50:50 joint venture with BBC Worldwide.
Webb will report directly to Neil Berkett, chief executive of Virgin Media, who said: "I'm delighted that Jonathan has agreed to take on this new challenge. In recent years, Living, Bravo, Virgin1 and Challenge have established themselves as the strongest brands in multichannel television and, under Jonathan's leadership, I'm confident that they can become stronger still."
Webb said: "VMTV's brands have already hit creative and ratings heights this year, and we're using that performance to deliver value for our advertisers, our programme suppliers and our platform partners.
"I'm looking forward to focusing the business on our vision of brilliant brands, delivered on every kind of screen."